Weeds generally fall into three categories—annual weeds, perennials, and biennial weed plants. Annual weeds that spread by seed can grow every year in new places. Perennial weeds produce long taproots and can be challenging to remove. Biennial weeds produce flowers in the first year and seeds in their second.

Weeds are essentially just plants growing where they are not wanted or needed. They can be cause problems gardens when they grow wild and compete with the plants you’ve worked hard to plant. Many types of weeds can spread from plant to plant, reproducing quickly and forming a large patch very quickly.

Many common weeds have "weed" in their name, like ragweed, knotweed, and chickweed. Weeds are often thought of as nuisance plants that invade lawns and gardens. If you can identify which plants are weeds, you can also learn how to control or eradicate these common types of weeds.